Kiln for revivifying char.



Patented 0017. 4, 1910.

R. S. KENT. KILN ron REVIVIFYING CHAR.

- APPLICATION FILED MAY 21, 1909.

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ITED STATES PATENT OFFICE.

ROBERT S. KENT, OF IBROOKLYN, NEW YORK.

KILN FOR REVIVIFYING CHAR.

To all whom it may concern:

Be it known that I, ROBERT S. KENT, a citizen of the United States, and a resident of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Kilns for Revivifying Char, of which the following is a specification.

The principal object of this invention is to improve the construction of kilns used in sugar refineries for the purpose of fully drying, and burning out organic waste material from, the animal charcoal or bone-black known as char generally used in sugar refining for removing coloring matter, etc., from the sugar liquors.

The present invention relates chiefly to the final drying and revivifying, that is, restoring to its working condition for reuse, of the char passing through the pipeshaped retorts of the kiln.

My improvements are directed particularly to increasing the etiiciency of the kiln. In these kilns as heretofore constructed the products of 4combustion from the tire-box have been brought almost immediately into contact with the lower ends of the retort pipes and the retorts most highly heated at their lower ends. The walls of the pipes forming these retorts generally vary in thick-v ness, being thickest at the tops and thinnest at the lower ends, and the hottest gases have heretofore been brought directly into contact with the lower ends of the retorts containing the dryest char, and cooler gases have heretofore been brought into contact with the thick upper ends of the retort pipes containing the wettest char and the greatest amount of impurities. In my invention the kiln is so constructed as to reverse this operation and bring the hottest products of combustion into contact first with the upper ends of the retort pipes where they are thickest and where the material should be most quickly and thoroughly dried. The means employed by me to accomplish this result also produces a more perfect combustion of the gases rising from the fuel, this result being due, first, to the fact that I provide a wall of great area in contact with the gases rising from the bed of fuel, which wall becomes highly heated and over which these gases pass, and second, to the fact that the draft is greatly increased as compared with kilns of the type heretofore used.

Specification of Letters Patent.

Application filed May 21, 1909.

Patented Oct. 4, 1910. Serial No. 497,299.4

In the drawings accompanying this speci- -fication and forming part of the present application, I have illustrated a kiln embodying this invention and capable of producing the results hereinbefore stated, Figure l being a substantially central vertical longitudinal section of the kiln, and Fig. 2 being partly a front elevation and partly a substantially central cross section of the same.

Similar characters designate like parts in the respective figures.

Most of the parts constituting the kiln are or may be of any well-known or suitable construction. In these kilns all of the walls are usually of brick, and this is the construction shown herein, the kiln being designated. generally by K, the front and rear walls by 2 and 3, and the side walls by l and 5. The kiln is also illustrated here as having an arched roof 6, of a type well understood in the art. Beneath the center of the kiln proper is a fire-box 7 having a grate 8, this lire-box extending in the present case about two-thirds of the way back from the front of the kiln and being tired only from the front, although the fire-box might ext-end all the way through and be fired from both ends, as in another type of kiln in general use. Kilns of this type contain a large number of retorts in the form of pipes eX- tending from the top to the bottom of the kiln, these pipes receiving their supplies ordinarily from a superimposed char-drier (not shown), and delivering the purified charcoal from their lower ends into coolertubes (not shown) located below the floor of the kiln. These retort pipes are ordinarily arranged in two sets at opposite sides of the fire-box and are so shown herein. The retorts of the different sets are designated respectively by 9 and 10. The walls of the retorts are generally of three different thicknesses, being thickest at the upper ends and thinnest at the lower ends, as illustrated in Fig. 2, while the intermediate portion is of an intermediate thickness. Retorts of this construction burn out quickly at their lower ends, because in kilns as heretofore made the most highly heated products of combustion were delivered directly in Contact with the lower ends of the retorts, where they are less able to resist the high temperature. In kilns of the old type the walls of these retorts disintegrated at the lower ends of the pipes, thus destroying the usefulness of the retorts, which then had to be replaced by new ones. Moreover, the cooler gases rising to the top of the kiln insufficiently heated the thick upper ends of the retorts, and the result was that the char descending through the retorts was not quickly dried nor were the organic impurities contained therein quickly reduced and driven out, the hotter gases acting upon the thin lower ends of the retorts being depended upon to complete the operation by driving a considerable percentage of the moisture, etc. out just before the purified char was delivered to the cooler tubes. Thus the moisture and impurities that should have been quickly driven out were not eliminated until they approached the lower ends of the retorts and then were compelled to travel through the whole mass of superimposed moist and clogged char before passing off through the upper ends of the retorts.

In the present kiln the hottest products of combustion are caused to pass directly to the thick upper ends of the tubes, which are best able to withstand their action, and a quick drying of the moisture and elimination of organic impurities is effected, the central thinner portions of the retorts and the lowermost and thinnest portions being heated by gases which are progressively cooler as they approach the lower ends of said retorts. Thus the circulation of the hot gases or products of combustion in my kiln is from the top toward the bottom of each retort instead of being from the bottom toward the top of each retort, as in kilns heretofore used. Because of this, the thin portions of the retorts are not only protected and the life of each retort prolonged, but the drying and purifying action is more perfectly effected, there being a smaller percentage of moisture and organic impurities to be driven ofl' from the lower ends of the retorts than in the old kilns, and the mass of char in the retorts being drier and less clogged, and hence in better condition to permit the escape of the last traces of moisture and impurities, than in the kilns heretofore used.

The construction employed by me for producing the circulation of the products of combustion in the direction just stated is one of the principal new features of this kiln. Any means suitable for the purpose may be employed, but I prefer to make use of one or more baffle-walls of relatively great height coperative with the lire-box and oner or both sets of retorts for the purpose of directing the products of combustion up to the upper portions of the retorts, after which they may pass down to the lower ends of said retorts. Two baffle-walls are shown herein for this purpose, one serving as a curtain-wall to screen a considerable portion of the length of each retort of one set from the greatest heat of the kiln and the other in a similar manner to screen the corresponding portions, that is, the lower ends, of the retorts of the other set. These walls may be of any suitable type and construction, provided they are of sufficient height to direct the major portion of the products of combustion up to the upper ends of the retorts. They are here illustrated at 11 as two like walls of brick rising to points adjacent to the lower ends of the thickest parts of the retort pipes. The line of the upper edge of each of these curtain-walls or baffle-walls l1 may be of any suitable contour, depending somewhat upon the shape of the roof of the kiln, each wall being here illustrated as of varying heights and highest at the front end of the kiln for the purpose of directing the hot gases toward the upper rear end of the same.

Another important feature of my invention is to obtain more perfect combustion of the fuel used and a greater economy in the operation of the kiln. This is preferably accomplished by the same means used to direct the circulation of the products of combustion, that is to say, the baffle-wall or baffle-walls just described, which in the operation of the kiln are highly heated at their inner sides and thus present a great area of heated surface over which the gases rising from the fire-box pass and by which more perfect combustion is obtained. An additional important advantage also resulting from the same construction is that the draft is very greatly increased owing to the fact that the products of combustion have to pass first to the top of the kiln and then descend to the bottom again before they can escape, the outlets being preferably placed at or near the bottom of the kiln and usually at opposite ends and sides, that is, at the four corners of the kiln, three of these outlets being designated respectively by 12, 13 and 14. As a result of this increased draft and the action of the highly heated inner surfaces of the battle-walls 11 on the gases passing thereover a cheaper grade of fuel may be used with a kiln of this type than with those heretofore employed and a corresponding economy effected. In addition to this the increased draft makes it practicable to reduce or do away with artificial draft. In the actual use of a large number of these kilns for many months a saving in cost of fuel has been effected, a more perfect puriiication of the char has resulted, the lower ends of the retorts have been more perfectly protected and the life of the same prolonged as a result of subjecting them to the action of cooler' gases and at the same time protecting them from the higher heat of the kiln by the thick walls 11 interposed between the retorts and the fire-box. Thus a more uniform and natural heating of the f il walls of the retorts results by reversing the direction in which the products of combustion were heretofore circulated and by screening the lower thin ends of the retorts. It will be clear that by this reversal of the direction of circulation of the gases the moisture in the char descending through the retorts will come at once on entering` the retorts into the zone of greatest heat and will be evaporated promptly. Because of this the efliciency of the lower portion of each retort is increased, as the char in the lower Zone is in a drier condition, which facilitates the reduction and elimination of the organic impurities vremaining in the char.

In some cases it may be found desirable to permit a portion of the products ot' coinbustion to pass directly to the lower parts of the retorts, in which case openings, such as 15, may be made in the bathe-walls 1l in the lower portion of the kiln. By properly determining the sizes and number of these openings any desired control of the application of heat to the upper and lower ends of the retorts may be obtained.

It is obvious of course that the walls l1 may vary considerably in height and indeed may be extended and connected at their upper ends either by a separate roof or at the root of the kiln, in which case the outlets will bc correspondingly modified. This change in construction, however, involves no modification of the principle here inbefore stated.

that I claim is:

1. In a kiln for-revivifying char, the combination with a tire-box, of a set of retort pipes constructed to be filled with char throughout their whole cross-sectional area bounded by their inner walls, and means for circulating the major portion of the products of combustion from said tire-box from the upper toward the lower ends of said retort pipes wholly outside of said pipes said means including a baillewall disposed lengthwise of the kiln between the fire-box and said set of retort-pipes and of sutlicient height to direct the heated products of combustion up to the upper portions of the retort-pipes.

2. In a kiln for revivifying char, the combination with a tire-box, of a set of retort pipes the walls of which are thickest at the upper ends and thinnest at the lower ends thereof, and means for circulating the major portion of the products of combustion from said fire-box in contact with first the thick upper portions and then the thin lower portions of said retort pipes.

3. In a kiln for revivifying char, the combination with a fire-box, of a set of retort pipes at one side of said ireboX, an outlet near the bottom of the kiln for the products of combustion, and a baille-wall disposed lengthwise ot the kiln between the iire-boX and said set of retort pipes and of sufficient height to direct the hottest products of combustion up to the upper portions of the retort pipes and cause said products of combustion to circulate downward from said point and out through said outlet.

et. In a kiln for revivifying char, the combination with a fire-box, of a plurality of re tort pipes arranged in sets at opposite sides of the lire-box, outlets near the bottom of the kiln at opposite sides thereof for the products of combustion, and a pair of baHle-walls disposed lengthwise of the kiln between the fire-box and the respective sets of retort pipes and of sutlicient height to direct the hottest products of combustion up to the upper portions of the retort pipes and cause said products of combustion to circulate downward from said points and out through said outlets.

In a kiln for revivifying char, the combination with a lire-box, of a set of retort pipes at one side of said lire-box, an outlet near the bottoni of the kiln for the products of combustion, and a battle-wall disposed lengthwise of the kiln between the fire-box and said set of retort pipes and of sufficient height to direct the hottest products of combustion up to the upper portions of the retort pipes, said wall being of. different heights at its opposite ends.

G. In a kiln for revivifying char, the combination with a tire-box, of a set of retort pipes at one side of said tire-box, an outlet near the bottom of the kiln for the products of combustion, and a bathe-wall disposed lengthwise of the kiln between the lire-box and said set oit' retort pipes and of sutlicient height to direct the hottest products of combustion up to the upper portions of the retort pipes, said wall being higher at the front end of the kiln than at the rear end.

7. In a kiln for revivifying char, the combination with a fire-box, of a plurality of retort pipes arranged in sets at opposite sides of the tire-box, outlets at opposite ends or' both sides of the kiln near the bottom thereof and adjacent to the respective sets of retort pipes for carrying off the products of combustion, and a pair of batllewvalls disposed lengthwise of the kiln between the fire-box and the respective sets of retort pipes and of sutlicient height to direct the hottest products of combustion up to the upper portions of the retort pipes and cause said products of combustion to circulate downward from said points and out through said outlets.

8. In a kiln for revivifying char, the combination with a lire-box, of a set of retort pipes at one side of said tire-box, an outlet near the bottom of the kiln for the products of combustion, and a bathe-wall disposed lengthwise of the kiln between the lire-box und said set of retort pipes` and of sufficient and into 'Contact 'with the lower portions of 10 height to direct the hottest products of cointhe retort pipes. hustion up to the upper portions of the re- Signed at New York, in the county of tort pipes and cause said products of oom- New York, and State of New York, this 5 bustion to circulate downward from said 15th day of May, A. D. 1909.

point and out through said outlet, said wall ROBERT S. KENT. having openings in the lower part of the VitneSSeS:

kiln to permit a portion of the products of C. S. CHAMPION,

combustion to pass directly therethrough R. CHAMPION. 

